The present invention relates in general to semiconductor devices and, more particularly, to integrated circuits having a low permittivity dielectric region for forming high frequency passive components.
The market for electronic systems continues to demand integrated circuits with increased functionality and a higher frequency capability. In response, semiconductor manufacturers are integrating increasing numbers of passive components on a semiconductor die along with active radio frequency (RF) circuitry. The increased integration levels are needed to reduce the cost and improve the performance of electronic systems operated at frequencies reaching five gigahertz and higher. So far, the integration of RF passive components and active circuits has been limited by the high fabrication cost of providing integrated passive components with the necessary frequency capability.
Some semiconductor manufacturers have addressed this problem by fabricating passive components on a low permittivity region of a semiconductor die in order to improve their frequency response by reducing their parasitic substrate capacitances. Low permittivity materials have been used to form these regions, but presently used materials either have a high cost or provide film thicknesses that are too thin to produce a sufficient reduction in parasitic capacitance. Other low permittivity regions are made with a thick dielectric film containing air pockets or voids that reduce the overall permittivity of the dielectric film. However, the air pockets have too small a volume because large amounts of dielectric material are redeposited in the air pockets while they are being sealed off. Moreover, the film thicknesses needed to seal off the air pockets add substantially to the difficulty and cost of the subsequent formation of transistors and other active devices.
Hence, there is a need for an integrated circuit with a lower permittivity region that improves the frequency capability of the integrated circuit while maintaining a low manufacturing cost.